Experimental, quantum chemical and Monte Carlo simulation studies on the corrosion inhibition of some alkyl imidazolium ionic liquids containing tetrafluoroborate anion on mild steel in acidic medium

The inhibition of mild steel corrosion in 1 M HCl solution by some imidazolium-based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM]+[BF4]−, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM]+[BF4]− and 1-decyl-3-methylimidazolium tetrafluoroborate [C10MIM]+[BF4]− was investigated using experimental and theoretical techniques. All the studied ILs showed appreciable inhibition efficiencies. Polarization measurements showed that the studied compounds are mixed-type inhibitors and the results obeyed Langmuir adsorption isotherm. Spectroscopic studies confirmed chemical interactions between mild steel and the ILs. Scanning electron microscopy images revealed that the inhibitors formed protective film on mild steel surface. The results of quantum chemical calculations and Monte Carlo simulations agree with experimental observations.